In an electric vehicle system, a battery pack is normally encased in a battery case with high structural rigidity to form a battery pack case that ensures the connection and protection of components in the battery pack case. Further, the entire battery pack case has sufficient rigidity and can be firmly fixed to the frame of the electric vehicle. Besides, a controller for propulsion of a motor of the electric vehicle has a circuit board that is required to be installed in a controller case. The battery pack case and the controller case are electric equipment case sets that aim at isolating the electric equipment sets therein, protecting the electric equipment sets against water infiltration or dust, and preventing the electric equipment sets from damages or short circuit.
The maximum operating temperature of the battery pack and the circuit board in the low-power electric vehicle can be set under safety control, and therefore a compulsory cooling mechanism is not required in most cases. The electric equipment case can even dissipate heat by itself due to air convection. Hence, the electric equipment case can have a closed structure and thereby easily achieve water-proof and dust-proof protection. However, with the development of electric vehicle technology, the electric vehicle is required to generate power to a greater extent and have prolonged cruising range, and thus the battery of the electric vehicle needs to have the increasing power, which leads to an increase in the temperature. Moreover, due to the significant power consumption of the motor in a high-power electric vehicle system, high-power components are required by the control circuit board for propelling the motor, thus raising the temperature of the system. Accordingly, the battery case and the controller case in the high-power electric vehicle system necessitate the advanced heat-dissipating and cooling mechanism in case that the overheated components are damaged or even endanger the drivers.
The forced air cooling achieves favorable cooling effects and costs less than the water cooling. Hence, the forced air cooling is applicable to the car electric equipment case set. In order to have the heat-dissipating air flow into or flow out of the electric equipment case in an unrestrained manner for dissipating heat of the electric equipment set in the electric equipment case, at least one air intake and at least one air exhaust need to be configured on the electric equipment case. Nonetheless, water that results from rain, splash driving, or car wash is likely to enter the electric equipment case through the air intake or the air exhaust thereon, and thereby the electric equipment set in the electric equipment case may be damaged. The foreign material, e.g., dust, may also enter the electric equipment case through the air intake or the air exhaust and contaminate the electric equipment set in the electric equipment case.